Awarded by Robert Silverberg on August 30, 1965 by Loncon II at a ceremony at Loncon II. To save shipping costs, there was only one Hugo trophy at the convention which each winner got to hold in turn.
Loncon II's categories basically followed those of the previous year's Pacificon II, including the one-year category Best Book Publisher which was never again awarded. However, in its nomination ballots it inadvertently left off Best Dramatic Presentation, apparently taking it list from Pacificon II's final ballot which left off Best Dramatic Presentation due to insufficient nominations. Protests were immediate and write-ins allowed the committee to include Best Dramatic Presentation on the final ballot, albeit with only two nominees.
Loncon II did not release standings after first, and placed an unusually small number of nominees on the final ballot: 2 in one category, 3 in two more and only 4 int he rest.
- 1965 Best Novel Hugo: The Wanderer by Fritz Leiber
- 1965 Best Short Fiction Hugo: "Soldier, Ask Not" by Gordon R. Dickson
- 1965 Best Dramatic Presentation Hugo: Dr. Strangelove
- 1965 Best Professional Magazine Hugo: Analog Science Fiction and Fact ed. by John W. Campbell, Jr.
- 1965 Best Professional Artist Hugo: John Schoenherr
- 1965 Best Fanzine Hugo: Yandro ed. by Robert Coulson and Juanita Coulson
- 1965 Best SF Book Publisher Hugo: Ballantine